The aim of this study is to track the dynamic alterations in nutrient intake and digestion, rumen fermentation and plasma metabolic characteristics, and rumen bacterial community of Holstein finishing steers in response to three nutrient density diets as fattening phases advanced. A total of eighteen Holstein steers were randomly allocated into three nutrient density groups and steers in each group were fed under a three-phase fattening strategy, with nutrient density increased in each group when fattening phase advanced. Results showed that both fattening phase and dietary nutrient density significantly influenced the nutrient digestion, most of the rumen fermentation parameters, and part of bacteria at phylum and genus levels. Individually, dietary nutrient density affected the concentrations of plasma alanine aminotransferase and urea N, bacterial richness and evenness. All determined nutrient intake and plasma biochemical parameters, except for alanine aminotransferase and triglyceride, differed among fattening phases. Spearman correlation analysis revealed strong correlations between fiber intake and bacterial richness and evenness, rumen fermentation characteristics and certain bacteria. Moreover, Patescibacteria abundance was positively correlated with ambient temperature and plasma total protein. These results indicate that rumen fermentation and nutrient digestion were influenced by both dietary nutrient density and fattening phase, and these influences were regulated by certain rumen bacterial community and ruminal bacteria may be affected simultaneously by ambient temperature. This study may provide insights into diet optimization and potentially adaptive mechanism of rumen bacterial community in response to fattening phases and gradually climatic change.

This study investigated the effect of dietary crude protein (CP) supplementation on nutrient intake, nitrogen (N) utilisation, blood metabolites, ruminal fermentation and growth performance of young Holstein bulls. Twenty-one young bulls weighing 277±11.2 kg were equally divided into three groups and were offered diets formulated with low CP (LCP; 10.21% CP and 4.22% rumen degradable protein [RDP]), medium CP (MCP; 12.35% CP and 5.17% RDP) and high CP (HCP; 14.24% CP and 6.03% RDP). Yellow corn silage was used as a unique forage source and was mixed with concentrate. This mixed feed was given ad libitum to the young bulls included in the study. Results showed that CP intake, blood urea nitrogen, N intake, total N excretion and N balance increased linearly with an increase in dietary CP level (p<0.05). However, no significant difference was observed in nutrient digestibility among the bulls receiving the different diets. Ruminal pH (p<0.05) and ammonia nitrogen (NH3-N) concentration (p<0.01) were significantly higher in the bulls receiving the MCP and HCP diets than in those receiving the LCP diet. The bulls receiving the HCP diet showed significantly higher ruminal bacterial protein level, propionate, acetate and total volatile fatty acid (TVFA) concentrations than bulls receiving the LCP diet (p<0.05). Moreover, dietary CP level exerted a significant positive effect on the final body weight, average daily gain and gain-to-feed ratio of the bulls (p<0.05). High dietary CP level is optimal for achieving maximum growth and high profitability without exerting a negative effect on the physiology of growing Holstein bulls.

This study evaluated the impact of Bacillus subtilis supplementation on growth, antioxidant status, digestive enzyme activities, hematological parameters, blood biochemistry, and immune responses in Nile tilapia (Oreochromis niloticus) fingerlings. A total of 180 fingerlings (mean weight: 5 ± 0.5 g) were randomly assigned to four groups: a control group and three probiotic-supplemented groups with 10⁶ (S-1), 10⁸ (S-2), and 10¹⁰ (S-3) CFU g⁻¹ of B. subtilis, following a completely randomized design. Fish were fed twice daily for eight weeks. Results showed that the 10¹⁰ CFU g⁻¹ group exhibited significantly higher weight gain (43 g), specific growth rate (2.5%/day), and better feed conversion ratio (0.7) compared to the control (30 g, 2.2%/day, and 1.4, respectively). Hematological parameters (WBC, RBC, hemoglobin) and immune responses (phagocytic activity, lysozyme) were significantly improved. Blood biochemistry showed decreased ALT/AST levels and increased ALP activity. Digestive enzymes (protease, lipase, amylase) and antioxidant activity (GPx, CAT, SOD) were enhanced, with reduced MDA levels. No significant differences were observed in survival rates or stress responses. These findings suggest that B. subtilis supplementation at 10¹⁰ CFU g⁻¹ improves growth, immune function, and antioxidant status, making it a promising probiotic for Nile tilapia.

The objective of this study was to explore whether collecting rumen samples of finishing steers at monthly intervals differed, and whether this difference or similarity varied with diets. For these purposes, 12 Chinese Holstein steers were equally divided into two groups. The dietary treatments were either standard energy and standard protein (C) or low energy and low protein (L). Rumen samples were obtained on day 30, day 60 and day 90 from both dietary treatments and were analyzed by using 16S rRNA gene sequencing. The results showed that monthly intervals had no effect on the richness and evenness of the rumen bacterial community in the two diets. However, taxonomic difference analysis (relative abundance >0.5%) revealed that the relative abundance of three phyla (Proteobacteria, Fibrobacteres and Cyanobacteria) and six genera (Rikenellaceae_RC9_gut_group, Ruminococcaceae_NK4A214_group, Fibrobacter, Eubacterium_coprostanoligenes_group, Ruminococcaceae_UCG-010 and Ruminobacter) were significantly different between monthly sampling intervals, and the difference was prominent between sampling in the first month and the subsequent two months. Moreover, the differences in abundances of phyla and genera between monthly sampling intervals were affected by diets. Analysis of similarity (ANOSIM) showed no significant differences between monthly sampling intervals in the C diet. However, ANOSIM results revealed that significant differences between the first month and second month and between the first month and third month were present in the L diet. These results indicated that temporal dynamics in rumen bacterial community composition did occur even after an adaptation period of three months. This study tracked the changes in rumen bacterial populations of finishing cattle after a shift in diet with the passage of time. This study may provide insight into bacterial adaptation time to dietary transition in finishing steers.

The current study was conducted to evaluate the effects of stored wheat-based diet (1.5 and 2.5 years stored wheat) with and without the supplementation of xylanase and phytase enzymes in combination or individually on performance parameters, digestibility, digesta viscosity and carcass characteristics of broilers. For this purpose, a total of 640-day-old male broilers were randomly distributed to the 64 pens, and each pen had 10 birds. Two basal isocaloric and isonitrogenous diets contained 1.5 and 2.5 years stored wheat were formulated in this experiment. In the current study, experimental feeds were prepared by supplementing exogenous enzymes in both basal diets with xylanase (500 XU), phytase (500 FTU) alone or in a combination of phytase and xylanase. Performance parameters data represents that both in starter phase and finisher phase, inclusion of exogenous enzymes xylanase and phytase in both basal diets alone or in combination enhance the feed intake, and body weight gain (p < 0.05) and improve the feed conversion ratio in overall phase (p < 0.05). Similarly, supplementation of exogenous xylanase and phytase alone or in combination enhance the nutrient digestibility and reduce the digesta viscosity (p < 0.05). Based on the results of this experiment, it is concluded that supplementation of exogenous xylanase and phytase enzymes alone or in combination in wheat-based diets (stored wheat 1.5 and 2.5 years) enhance and improves the performance of birds.